The goal of this proposal is to use liposome-mediated neurotrophin gene transfection to develop efficient and clinically relevant gene therapies to treat traumatic brain injury (TBI). Enhanced expression of neurotrophins produced by liposome-mediated gene transfection may have therapeutic potential for treatment of TBI. A highly focused in vitro research program is an essential prerequisite for the development of in vivo applications. Aim 1: Use different cDNA to liposome ratios, concentrations and incubation times to deliver cDNA-liposome complexes in order to evaluate transfection efficiency and duration of transgene expression in primary septo-hippocampal cell cultures. Aim 2: Test the potential toxic effects of different types and concentrations of liposomes as well as incubation times on CNS cell cultures. Aim 3: Examine the biological activity of neurotrophins and their ability to facilitate recovery from neuronal injury after applying optimized neurotrophin cDNA-liposome complexes into CNS cultures. Aim 4: Explore liposome-mediated gene transfection in uninjured and mechanically injured rat brains. We have provided substantial data from coordinated in vitro studies indicating that liposome-mediated transfection of CNS cells can provide increases in mRNA and protein of neurotrophins (NGF, BDNF). We have shown that appropriate transfection protocols, which have minimal toxicity, can produce biologically active neurotrophins and enhance recovery from cholinergic deficiencies. Moreover, we have successfully transfected a reporter gene as well as neurotrophin genes into the uninjured and injured rat brain. The proposed studies represent the first systematic effort to examine the use of non-viral vectors to transfect neurotrophins into CNS cells in order to facilitate recovery from CNS injury. Minimally, the research will provide critical information on the efficiency of liposomal transfection of neurotrophins and essential initial data on the clinical potential of this approach to treat traumatic injury to the central nervous system.